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  Subjects -> CHEMISTRY (Total: 846 journals)
    - ANALYTICAL CHEMISTRY (47 journals)
    - CHEMISTRY (597 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (26 journals)
    - INORGANIC CHEMISTRY (42 journals)
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    - PHYSICAL CHEMISTRY (67 journals)

ANALYTICAL CHEMISTRY (47 journals)

Showing 1 - 0 of 0 Journals sorted alphabetically
Accounts of Chemical Research     Full-text available via subscription   (Followers: 86)
Acta Analytica     Hybrid Journal   (Followers: 7)
Advances in Analytical Chemistry     Open Access   (Followers: 21)
American Journal of Analytical Chemistry     Open Access   (Followers: 27)
Analytica Chimica Acta     Hybrid Journal   (Followers: 39)
Analytical and Bioanalytical Chemistry     Hybrid Journal   (Followers: 32)
Analytical Chemistry     Full-text available via subscription   (Followers: 218)
Analytical Chemistry Insights     Open Access   (Followers: 17)
Analytical Chemistry Research     Open Access   (Followers: 2)
Analytical Letters     Hybrid Journal   (Followers: 11)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 9)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 9)
Biomonitoring     Open Access  
Chinese Journal of Analytical Chemistry     Full-text available via subscription   (Followers: 3)
Combinatorial Chemistry - an Online Journal     Open Access   (Followers: 2)
Comprehensive Analytical Chemistry     Full-text available via subscription   (Followers: 5)
Critical Reviews in Analytical Chemistry     Hybrid Journal   (Followers: 24)
Current Analytical Chemistry     Hybrid Journal   (Followers: 7)
Drug Testing and Analysis     Hybrid Journal   (Followers: 6)
Electroanalysis     Hybrid Journal   (Followers: 5)
Field Analytical Chemistry and Technology     Hybrid Journal   (Followers: 4)
Handbook of Analytical Separations     Full-text available via subscription   (Followers: 1)
Handbook of Thermal Analysis and Calorimetry     Full-text available via subscription  
International Journal of Analytical Chemistry     Open Access   (Followers: 21)
International Journal of Chemical and Analytical Science     Full-text available via subscription   (Followers: 3)
International Journal of Environmental Analytical Chemistry     Hybrid Journal   (Followers: 6)
International Journal of Polymer Analysis and Characterization     Hybrid Journal   (Followers: 5)
Journal of Analytical & Bioanalytical Techniques     Open Access   (Followers: 6)
Journal of Analytical Atomic Spectrometry     Full-text available via subscription   (Followers: 10)
Journal of Analytical Chemistry     Hybrid Journal   (Followers: 19)
Journal of Electroanalytical Chemistry     Hybrid Journal   (Followers: 4)
Journal of Essential Oil Research     Hybrid Journal   (Followers: 1)
Journal of Radioanalytical and Nuclear Chemistry     Hybrid Journal   (Followers: 5)
Journal of Thermal Analysis and Calorimetry     Hybrid Journal   (Followers: 22)
Main Group Metal Chemistry     Hybrid Journal   (Followers: 1)
Microchemical Journal     Hybrid Journal   (Followers: 3)
Nigerian Journal of Chemical Research     Full-text available via subscription  
Phytochemical Analysis     Hybrid Journal   (Followers: 2)
Polish Journal of Chemical Technology     Open Access   (Followers: 1)
Reviews in Analytical Chemistry     Hybrid Journal   (Followers: 9)
Sample Preparation     Open Access  
Surface and Interface Analysis     Hybrid Journal   (Followers: 13)
Techniques and Instrumentation in Analytical Chemistry     Full-text available via subscription   (Followers: 5)
TrAC Trends in Analytical Chemistry     Full-text available via subscription   (Followers: 53)
Trends in Environmental Analytical Chemistry     Hybrid Journal   (Followers: 2)
Vibrational Spectroscopy     Hybrid Journal   (Followers: 11)
World Journal of Analytical Chemistry     Open Access   (Followers: 1)
Journal Cover Journal of Analytical Chemistry
  [SJR: 0.33]   [H-I: 19]   [19 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1608-3199 - ISSN (Online) 1061-9348
   Published by Springer-Verlag Homepage  [2335 journals]
  • Development and validation of stability indicating analytical method for
           Ilaprazole
    • Abstract: The objective of the present study was to develop and validate a rapid and simple stability indicating analytical method for estimating Ilaprazole. Ilaprazole was subjected to different stress conditions prescribed by International Conference on Harmonization (ICH) such as hydrolysis, oxidation, photolytic and dry heat degradation conditions. The drug was very susceptible to degradation under hydrolysis and photolytic conditions, less susceptible to oxidation and stable under dry heat degradation condition. An acceptable separation of drug and its degradants was achieved by using a C-18 column and mobile phase composed of ammonium acetate buffer (pH 3.2)—acetonitrile (55: 45, v/v). Flow rate was 1 mL/min and detection wavelength was set at 303 nm. Retention time of drug was found to be 6.6 min and analysis can be completed within 10 min. The method was validated with respect to linearity, precision, accuracy, robustness, LOD and LOQ as per ICH. The method was linear (R 2 = 0.996) in the range of 2.5–250 μg/mL. The recovery was in the range from 99.2–100.2%.
      PubDate: 2016-06-01
       
  • Separation of some phenolic acids in micellar liquid chromatography using
           design of experiment-response surface methodology
    • Abstract: Derringer’s desirability function combined with face-centered cube central composite design was used to map the chromatographic response surface for simultaneous optimization of resolution and analysis time of four phenolic acids (vanilic, cafeic, para-coumaric and ferulic) in micellar liquid chromatography. The factors studied were the concentration of sodium dodecyl sulfate (SDS), volume percentage of propanol (PrOH), and acetic acid (AcOH) in mobile phase. The chromatographic response functions (CRFs) were formed using two sigmoidal desirability functions. The quality of the obtained chromatograms in each experiment was calculated using CRF, and the model was built by the use of multiple linear regression (MLR) to correlate the obtained CRFs with the experimental factors and their interactions. The developed MLR model showed good descriptive and predictive ability (R 2 = 0.9569 and F = 24.45). The optimum mobile phase composition was found to be [SDS] = 20 mM, 1.0% (v/v) PrOH and 2.0% (v/v) AcOH, which provided good resolution and analysis time for the separation of target phenolic acids. The efficiency of prediction of polynomial model was confirmed by performing the experiment under the predicted optimal conditions.
      PubDate: 2016-06-01
       
  • Compound identification in metabolomics: a study with the use of two
           different GC data processing systems
    • Abstract: The present paper reports a comparison study of two data processing procedures in GC–MS metabolome components investigation based on two modern softwares: Automated Mass Spectral Deconvolution and Identification System (AMDIS) and GC–MS Solution Postrun Analysis (GC–MS SPA). GC–MS SPA is intended for manual integration and identification, while AMDIS is proposed as a fast, and automatic data analysis tool. Both methods are based on the same free-access library. In the present study, 12 compounds previously detected in a metabolomic fingerprint of grasshopper abdominal secretion, were tested at three concentration levels: 2.5, 5 and 10 μg/mL. The processing procedures were evaluated by comparison of peak area ratio for each tested concentration. The obtained results proved that processing with the use of AMDIS was more sensitive and enabled the identification of all compounds at the lowest selected concentration. Additionally, the differentiation of structurally similar compounds was possible with the use of AMDIS software.
      PubDate: 2016-06-01
       
  • Molar absorption coefficient of ozone in aqueous solutions
    • Abstract: The value of the molar absorption coefficient of ozone in aqueous solutions (2992 ± 71 M–1 cm–1 at 260 nm) is found based on the determination of ozone concentration by iodometry. This value is confirmed by the results of determination of O3 concentration by reaction with the bromide ion and virtually coincides with the maximum absorption coefficient of ozone in the gas phase in the region the Hartley band. In the determinations of ozone concentration in aqueous solutions by direct spectrophotometry, we recommend the value of the molar absorption coefficient ε(О3)260 = 3000 M–1 cm–1.
      PubDate: 2016-06-01
       
  • Specific features of determinations of the composition of high-purity
           lanthanide crystal hydrates
    • Abstract: Problem of the determination of the composition of high-purity rare-earth metal salts is discussed. Prospects of the application of direct chemical methods to the determination of the water content of crystal hydrates of rare-earth metal salts used in the GET 173-2013 State Primary Standard of Mass Fraction and Mass (Molar) Concentration of Water in Solid and Liquid Substances and Materials are studied.
      PubDate: 2016-06-01
       
  • Flotation-assisted dispersive liquid–liquid microextraction method
           for preconcentration and determination of trace amounts of cobalt:
           Orthogonal array design
    • Abstract: A simple, rapid, and efficient flotation-assisted dispersive liquid–liquid microextraction method was developed for preconcentration of trace amount of cobalt(II) ions. In this technique, a mixture of toluene and methanol (20: 80, v/v) was injected through the septum in the bottom of a narrow-bore tube containing cobalt solution. Afterwards, the fine droplets of extraction solvent were formed and cobalt (as 1-nitroso-2- naphtol complex) was collected on the surface of solution by aeration. The effect of different variables on the extraction efficiency of cobalt such as pH of solution, ligand concentration and injection volume was investigated using orthogonal array design. At optimum conditions, the calibration curve was linear over the range of 10–1000 μg/L. The detection limit, relative standard deviation and enrichment factor were 3 μg/L, 3.9% (n = 10) and 120, respectively. The developed method was successfully applied to the determination of cobalt in water and drug samples.
      PubDate: 2016-06-01
       
  • Processing of NMR, UV, and IR spectrometric data prior to chemometric
           simulation by independent component and principal component analysis
    • Abstract: We consider methods for the mathematical preprocessing of signals in the spectrometric analysis of multicomponent mixtures using chemometric algorithms aimed at adjusting the baseline, experimental noise, and random shift of spectral bands. Practical examples of using simple mathematical operations (scaling, centering, derivatization) are given. The effectiveness of algorithms is illustrated by a wide range of spectroscopic signals (electronic absorption, IR, and NMR spectra) combined with chemometric methods of principal component analysis and independent component analysis.
      PubDate: 2016-06-01
       
  • A flow-injection amperometric method for determining antiviral guanine
           derivatives
    • Abstract: A flow-injection method is proposed for determining antiviral guanine derivatives, acyclovir, valacyclovir, ganciclovir, and famciclovir, based on their amperometric detection on a carbositall electrode with a preactivated surface. The method is characterized by a wide analytical range, relatively low detection limits (0.6–1.2 μg/mL), and high performance (75 h–1). The results of examination of the accuracy and reproducibility of the analysis of solutions of different pharmaceutical forms containing the test substances are presented. The potentials of the developed flow-injection method in the implementation of the “Dissolution” test in an automated mode are demonstrated.
      PubDate: 2016-06-01
       
  • HPLC—high-resolution time-of-flight mass spectrometry:
           Identification and determinarion of β-agonists in food and feed
    • Abstract: A method is proposed for the simultaneous identification and determination of 19 β-agonists by exact ion masses in feed, meat, liver, and kidneys of animals using high-resolution time-of-flight mass spectrometry combined with HPLC and simple and fast sample preparation. Matrix effects under the conditions of electrospray ionization were eliminated by the dilution of the extract with a 10-fold volume of deionized water. A scheme of the identification and determination of analytes by the standard addition method is proposed. The limits of detection are 0.11–10 ng/g and limits of quantification, 0.34–31 ng/g. The relative standard deviation of the results of analysis does not exceed 13%. The time of analysis is 1–2 h.
      PubDate: 2016-06-01
       
  • Simultaneous determination of trimethoprim, enrofloxacin, and
           ciprofloxacin in blood serum of poultry
    • Abstract: A method is proposed for the simultaneous determination of trimethoprim, enrofloxacin, and ciprofloxacin in blood serum of poultry using HPLC. Samples were prepared using protein precipitation. The chromatographic separation of substances was attained on a C18 column using a mixture of a 50 mM acetate buffer solution (pH 3.0) with acetonitrile (86: 14) as a mobile phase. Detection was performed at 278 nm. Linearity was observed in the concentration range 50–5000 ng/mL for trimethoprim and 10–5000 ng/mL for ciprofloxacin and enrofloxacin. Precision was ≤2.1% for enrofloxacin, ≤1.6% for ciprofloxacin, and ≤14% for trimethoprim. Accuracy was ≤10.2% for enrofloxacin, ≤9.9% for ciprofloxacin, and ≤11.9% for trimethoprim. The method was applied to pharmacokinetic studies of complex antibacterial drugs containing trimethoprim and enrofloxacin as active substances.
      PubDate: 2016-06-01
       
  • X-ray fluorescence determination of the surface density of thin chromium
           and iron films using reference samples of elements with close atomic
           numbers
    • Abstract: In X-ray fluorescence determinations of the surface density of thin chromium and iron films, we studied the possibility of using an approach based on the application of reference samples of elements with close atomic numbers. It was shown that the proposed diagnostic approach ensures the determination of the surface density of films with rather high precision.
      PubDate: 2016-06-01
       
  • Determination of lipids and their oxidation products by IR spectrometry
    • Abstract: We proposed a procedure for the IR spectrometric determination of lipid hydroperoxides in biological systems. The main bands in the IR absorption spectra of linoleic acid and its hydroperoxide were identified, and analytical bands suitable for the determination of both compounds in their mixtures were selected. It was demonstrated that tert-butyl hydroperoxide can be used as an external standard for determining fatty acid hydroperoxides. Using the external standard method (calibration curve) for tert-butyl hydroperoxides, we calculated the concentration of linoleic acid hydroperoxide in its mixture with linoleic acid; it agreed with the specified values. Using the developed procedure, we estimated the concentration of hydroperoxide groups in natural cardiolipin. The results were compared to those obtained by an independent method (activated chemiluminescence).
      PubDate: 2016-06-01
       
  • Determination of the antioxidant capacity of the micellar extracts of
           spices in Brij® 35 medium by differential pulse voltammetry
    • Abstract: It was established that the micellar extracts of spices are electrochemically active on a glassy carbon electrode modified with cerium dioxide nanoparticles in a 0.02 M Brij® 35 in the presence of a phosphate buffer solution (pH 7.4) under the conditions of differential pulse voltammetry. The number of oxidation steps and their potentials vary over a wide range depending on the type of spice. A number of the oxidation peaks of the micellar extracts of spices were identified based on the oxidation potentials of the following individual antioxidants: gallic acid, ferulic acid, p-coumaric acid, caffeic acid, rosmarinic acid, thymol, eugenol, vanillin, syringaldehyde, capsaicin, rutin, quercetin, catechin, tannin, and curcumin. The contribution of the main antioxidants to the amperometric response of the extracts was confirmed by the standard addition method. A procedure for the voltammetric determination of the antioxidant capacity of the extracts of spices based on the oxidation of their antioxidants was developed. The antioxidant capacity of spices was evaluated from the total area of the oxidation steps in units of gallic acid, whose analytical range, detection limit, and determination limit were 50–2490, 11.9, and 39.6 μM, respectively. Twenty types of spices were analyzed. Positive correlations of the antioxidant capacity with the ferric reducing power and the antioxidant activity (r = 0.8971 and 0.9127, respectively at r crit = 0.497) were found.
      PubDate: 2016-06-01
       
  • Determination of glycols in glycol-containing oligomers using gas-liquid
           reaction chromatography
    • Abstract: A method is proposed for the gas-chromatographic determination of glycols as bis(diethoxyphosphoryl) alkanes formed by the Atherton–Todd reaction with diethyl phosphite. Gas-chromatographic and mass-spectrometric characteristics of the derivatives obtained are studied. Conditions of the phosphorylation reaction are optimized. The method is applied to the determination of the residual amounts of glycols in oligomeric glycol-o-phthalates.
      PubDate: 2016-06-01
       
  • Investigation of electrochemical behavior and development of a validated
           adsorptive stripping square wave voltammetry method for 3-nitrotyrosine in
           human plasma and cerebrospinal fluid
    • Abstract: An adsorptive stripping square wave voltammetric (AdSqW) method was developed for the determination of 3-nitrotyrosine (3-NT), a biomarker of in vivo oxidative damage in Alzheimer, ALS, Parkinson’s, cardiovascular diseases and cancer, in some biological fluids. Voltammetric measurements were performed in 0.30 M (pH 9.0) phosphate solution as supporting electrolyte, a reduction peak was observed at–0.487 V (vs. Ag/AgCl–3 M KCl) with a hanging mercury drop electrode by square wave voltammetry. Cyclic voltammetric measurements showed that the current was adsorption-controlled. LOD and LOQ values were as 0.25 and 1.5 nM, respectively, for the AdSqW method. 3-NT was determined in plasma and cerebrospinal fluid using AdSqW method, which allowed to work at low concentrations. Recovery value was measured as 96.3 ± 2.3%.
      PubDate: 2016-06-01
       
  • Gas-chromatographic determination of the degree of conversion of
           microbiological synthesis products into biodiesel
    • Abstract: In the development of promising methods for the production of biodiesel from different raw materials, it was proposed to perform the comparative evaluation of the degree of conversion of the source material and the effectiveness of the heterogeneous catalyst used by the gas-chromatographic determination of the resulting amount of glycerol with the direct injection of a reaction mixture (or end products) into the column without derivatization. A Bruker 430 GS gas chromatograph with a flame-ionization detector and a quartz capillary column in the isothermal regime was used for determining the glycerol formed. The degree of conversion was evaluated in a study of the transesterification of sunflower oil and microalgae lipids with the use of the enzyme catalyst Novozym 435. For comparison, the degree of conversion was determined by HPLC–MS based on the triglyceride content of the reaction mixture.
      PubDate: 2016-06-01
       
  • Synthesis and characterization of a liquid crystal containing oxadiazole
           and its performance for the separation of isomers by gas chromatography
    • Abstract: Liquid crystals are used as the stationary phase in gas chromatography to separate close-boiling isomers. In this paper, a new nematic liquid crystal containing oxadiazole was prepared by condensation of the amino group of 4-(5-(ethylthio)-1,3,4-oxadiazole-2-yl)aniline and the aldehyde group of p-methoxy-benzaldehyde. The compound was characterized by NMR, IR, X-ray diffraction, polarized light microscopy, and differential scanning calorimetry. The liquid crystal was used as the stationary phase in gas chromatography, and the nematic phase separated a variety of isomers, such as benzene derivatives, ionone, and citral.
      PubDate: 2016-05-01
       
  • Adsorption of Eu(III) ions on silicas with noncovalently immobilized
           thiacalix[4]arene derivatives
    • Abstract: Using the noncovalent immobilization of some thiacalix[4]arene derivatives on the surface of silanized silica, we obtained efficient adsorption materials for the extraction of Eu(III) ions from aqueous solutions of medium mineralization. The specific surface area of the adsorbents is 200–370 m2/g. It is shown that adsorbents containing thiacalix[4]arenes with phosphoryl groups selectively extract up to 99% of europium ions from aqueous solutions at pH 5.5–6; they are characterized by adsorption capacity of 7.5–14.5 mg/g and high distribution coefficients. The studied adsorbents exhibit high selectivity with respect to Eu(III) ions, wherein the distribution coefficients for Cs, Sr, Tb(III), Sm(III), Gd(III), La(III), and UO 2 2+ are five times or more smaller.
      PubDate: 2016-05-01
       
  • Determination of four lignanoids in roots, stems and leaves of Zanthoxylum
           armatum DC by HPLC-DAD with HPLC-ESI–QTOF-MS confirmation
    • Abstract: A rapid, effective method through an orthogonal design was developed, and four lignanoids were determined by HPLC and confirmed by HPLC coupled with electrospray ionization and quadrupole timeof-flight mass spectrometry (HPLC-ESI–QTOF-MS). The roots, stems and leaves of Zanthoxylum armatum DC were extracted by methanol for 15 min under reflux. Separation was performed using an UPLC system to quantify four bioactive compounds, namely fargesin, asarinin, planispine A and planispine B, in 12 batches of samples of different origin from China. Furthermore, the samples were analyzed using HPLC-ESI–QTOF-MS to confirm the results. The calibration curves of all four analytes showed good linearity (R > 0.998). Accuracy, precision and repeatability were all within required limits. The mean recoveries measured at the three concentrations were higher than 99% with RSDs lower than 4.1%. The established HPLC-DAD method could serve as a rapid and effective method for quality evaluation of Zanthoxylum armatum DC.
      PubDate: 2016-05-01
       
  • Experimental observation and numerical simulation of spectra of
           solid-anode X-ray tubes
    • Abstract: Possibilities of the experimental measurement and theoretical modeling of a fluorescence spectrum of a solid-anode X-ray tube are studied. A setup for the direct measurement of spectra of X-ray tubes of different types is created, spectra of a commercial BKh15 Svetlana X-ray tube are measured in wide range of anode voltages and currents. Calculations of spectra using the Ebel algorithm (Horst Ebel, 2006) with the parameters recommended in the original work ensure the satisfactory quality of the reproduction of the measured spectra, but demonstrate some statistically noticeable deviations. The optimization of model parameters ensures the improvement of the quality of simulation.
      PubDate: 2016-05-01
       
 
 
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